Re: [Qemu-devel] [PATCH v2 1/3] block: Extrace bdrv_parse_detect_zeroes_flags

[Fam Zheng <famz@redhat.com>]

On Mon, 06/08 16:53, Paolo Bonzini wrote:
> 
> 
> On 08/06/2015 16:17, Eric Blake wrote:
> >> > +
> >> > +    if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
> >> > +        !(bdrv_flags & BDRV_O_UNMAP)) {
> >> > +        error_setg(errp, "setting detect-zeroes to unmap is not allowed "
> >> > +                         "without setting discard operation to unmap");
> >> > +    }
> > I think it might be better to have a tri-state enum, than to have two
> > competing bools where only 3 of the 4 states are valid.
> 
> Note that this is not a bool.  We have one bool and one 3-element enum
> (off/on/unmap), where only 5 of the 6 states are valid.  Also, at least
> detect-zeroes would go away if we had some kind of blockdev-mirror
> (where the target is added first with blockdev-add), so I think it's
> better to leave it separate.

Agreed. But by then "drive-mirror derive=... detect-zeroes=unmap unmap=false"
will be way too confusing.

I say let's save that and just go for blockdev-add :)

https://www.mail-archive.com/qemu-devel@nongnu.org/msg301990.html

Fam